add a test that checks that each errorcode has a string representation

errorcodes/error_code.go

@@ -0,0 +1,4 @@
+package errorcodes
+
+// An ErrorCode in QUIC
+type ErrorCode uint32

errorcodes/error_codes.go

@@ -1,12 +1,7 @@
-// Package errorcodes defines the error codes in QUIC.
-//
 package errorcodes
 
-// An ErrorCode in QUIC
-type ErrorCode uint32
-
 // The error codes defined by QUIC
-// Remeber to run go generate ./... whenever the error codes change.
+// Remeber to run `go generate ./...` whenever the error codes change.
 //go:generate stringer -type=ErrorCode
 const (
 	InternalError      ErrorCode = 1

errorcodes/errorcodes_test.go

@@ -0,0 +1,40 @@
+package errorcodes_test
+
+import (
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"os"
+	"strconv"
+
+	"github.com/lucas-clemente/quic-go/errorcodes"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"testing"
+)
+
+func TestErrorcodes(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Errorcodes Suite")
+}
+
+var _ = Describe("error codes", func() {
+	// If this test breaks, you should run `go generate ./...`
+	It("has a string representation for every error code", func() {
+		// We parse the error code file, extract all constants, and verify that
+		// each of them has a string version. Go FTW!
+		filename := os.Getenv("GOPATH") + "/src/github.com/lucas-clemente/quic-go/errorcodes/error_codes.go"
+		fileAst, err := parser.ParseFile(token.NewFileSet(), filename, nil, 0)
+		Expect(err).NotTo(HaveOccurred())
+		constSpecs := fileAst.Decls[0].(*ast.GenDecl).Specs
+		Expect(len(constSpecs)).To(BeNumerically(">", 4)) // at time of writing
+		for _, c := range constSpecs {
+			name := c.(*ast.ValueSpec).Names[0].Name
+			valString := c.(*ast.ValueSpec).Values[0].(*ast.BasicLit).Value
+			val, err := strconv.Atoi(valString)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(errorcodes.ErrorCode(val).String()).To(Equal(name))
+		}
+	})
+})